Comparison of environmental performance-HSEQ management system, regarding the International and Iranian oil and gas contractorsJafar Nouri1, Majid Abbasspour2, Emad Roayaie2 and Hanieh Nikoomaram2, (1)School of Public Health, University of Tehran Medical Sciences, Iran; (2)Islamic Azad University, Science and Research Campus, Graduate College of the Environment and Energy, Iran